For many video camera applications, e.g. monitoring applications, it is advantageous to use a camera which can pan, tilt (and optionally zoom and/or rotate) to cover a large area. Such camera is known under the name PT (pan-tilt) camera, PTZ (pan-tilt-zoom) camera etc. The PT functionality may also be provided by the camera being mounted on a so called PT head, which is a motorized mounting base which can pan and tilt a camera mounted thereon. During e.g. a pan/tilt motion of the camera, the bit rate of a video stream captured by the camera can reach high levels. This is due to the fact that the adjustment within the video stream, i.e. between two consecutive image frames within the video stream, makes P-block encoding difficult to achieve. Consequently, most or all pixel blocks within an image frame are encoded using costly I-blocks during such adjustment, leading to an increased bit rate.
Within video processing there is a continuing effort put into reducing the bit rate while maintaining a perceived quality of the video stream. A solution to the above problem is to adapt a motion vector search range of the encoder encoding the video stream according to the speed of the pan/tilt adjustment. Since searching for matching blocks of pixels between two images usually requires a large amount of arithmetic computation and an increase motion vector search range lead to that more comparisons is made, a problem with this solution is that the computational complexity of the encoding process will increase, thus requiring more processor power and/or increase processing time for completing the encoding process.
There is thus a need for improvements within this context.